CFIDS Disability Scale

by David S. Bell, M.D.

The Doctor's Guide to Chronic Fatigue Syndrome - Understanding, Treating, and Living with CFIDS (1994)

Chapter 9 "The Measurement of Disability," pages 122-4

One defining aspect of CFIDS [Chronic Fatigue and Immune Dysfunction Syndrome] is that with rest, many people feel relatively well, but symptoms flare up with exertion or activity. Some people with CFIDS will have three or fours hours a day when they feel relatively well, most commonly in the afternoon, the "activity window." It is during this time that they can shop or do activities outside the house with less difficulty. The disability in CFIDS is not the same as in cancer or multiple sclerosis where performance level is constant during the day and constant from day to day. Any good measure of the disability status in this illness needs to take these variables into account.

For the physician seeing a patient with CFIDS, it is useful to measure level of activity and ability to function with a simple instrument on every visit. This will document clinical improvement or its absence, note medication effects, and serve as a useful marker to the disability analyst. Moreover, it will help communicate that the disability and limitations claimed have been observed and taken seriously by the physician. Doctors dislike filling out tedious disability claims; their job is medical, not legal. But it is part of the physician's responsibility, and having good documentation over a period of time makes the process much easier.

One such instrument is the CFIDS Disability Scale, reproduced on the following page. The patient can fill it out while waiting for an office visit, and the physician may modify it with notes if necessary. It is a rating scale similar to other instruments but modified with a greater range in the area of disability seen in CFIDS. The attempt is to document as accurately as possible the severity of symptoms, the degree of activity impairment with both activity and rest, and the functional ability regarding full-time work. The principle behind this rating scale is that symptom severity is often related to exertion. This is bewildering to a disability analyst who says, "When you are sick, you're sick-not When you work, you're sick." The score assigned should be closest to the overall degree of limitation.

This disability rating scale has been developed in our office, and any physician wishing to use it may feel free to do so.

One problem with this instrument is that it is new and has not been validated with large-scale scientific studies. It has the potential problem that a patient may be at a score of 50 in one area but a score of 30 in another, and in this case the physician may make the overall determination. A further problem is that it is subjective, and the scores may differ from physician to physician. Yet despite these limitations, this scale does give a general score that may be applicable to the type of disability seen in CFIDS.

CFIDS Disability Scale

100: No symptoms at rest; no symptoms with exercise; normal overall activity level; able to work full-time without difficulty.

90: No symptoms at rest; mild symptoms with activity; normal overall activity level; able to work full-time without difficulty.

70: Mild symptoms at rest; some daily activity limitation clearly noted. Overall functioning close to 90% of expected except for activities requiring exertion. Able to work full-time with difficulty.

60: Mild to moderate symptoms at rest; daily activity limitation clearly noted. Overall functioning 70%-90%. Unable to work full-time in jobs requiring physical labor, but able to work full-time in light activity if hours flexible.

50: Moderate symptoms at rest. Moderate to severe symptoms with exercise or activity; overall activity level reduced to 70% of expected. Unable to perform strenuous duties, but able to perform light duty or desk work 4-5 hours a day, but requires rest periods.

40: Moderate symptoms at rest. Moderate to severe symptoms with exercise or activity; overall activity level reduced to 50%-70% of expected. Not confined to house. Unable to perform strenuous duties; able to perform light duty or desk work 3-4 hours a day, but requires rest periods.

30: Moderate to severe symptoms at rest. Severe symptoms with any exercise; overall activity level reduced to 50% of expected. Usually confined to house. Unable to perform any strenuous tasks. Able to perform desk work 2-3 hours a day, but requires rest periods.

20: Moderate to severe symptoms at rest. Unable to perform strenuous activity; overall activity 30%-50% of expected. Unable to leave house except rarely; confined to bed most of day; unable to concentrate for more than 1 hour a day.

10: Severe symptoms at rest; bedridden the majority of the time. No travel outside of the house. Marked cognitive symptoms preventing concentration.